This invention relates to a packaging material for a photographic photosensitive material.
Packaging materials for photographic photosensitive material require various properties as well as complete light-shielding ability, such as slitting ability, gas barrier, moistureproofness, rigidity, physical strength (rupture strength, tear strength, impact puncture strength, Gelbo test strength, resistance to abrasion, etc.), heat sealing properties (heat seal strength, slitting sealability, hot tack properties, sealability with other materials, etc.), antistatic ability, flatness, lubricity, and the like.
On the other hand, complete sealing transparent packaging materials with a print are used for the packages using an injection molded article having complete light-shielding ability, such as light-shielding magazine or light-shielding cartridge. Examples of such a package are photographic films placed in a cartridge, photographic film units with a lens, advanced photo system films, and the like.
Heretofore, various packaging materials were developed for packaging photographic photosensitive material, such as photographic film. For example, a film for packaging photosensitive material disclosed in Japanese Patent KOKOKU 2-2700 comprises a light-shielding film containing 50 wt. % or more of L-LDPE resin and 1 wt. % or more of light-shielding material.
A packaging material for photographic photosensitive material disclosed in Japanese Patent KOKOKU 4-80372 is formed of a polyolefin resin composition comprising 50 to 95 wt. % L-LDPE resin and 5 to 49.5 wt. % HDPE resin and further containing 0.1 to 10 wt. % carbon black and 0.01 to 10 wt. % lubricant.
A packaging material for photographic photosensitive material disclosed in Japanese Patent KOKOKU 4-80373 is a coextruded double layer inflation film consisting of a HDPE resin layer or polypropylene resin layer and an L-LDPE resin layer.
A package of photographic roll film of the size 120 or 220 provided with bar code at a bonding tape which can be read automatically by a camera to know its sensitivity, etc. is disclosed in Japanese Patent KOKAI 9-80695. The package uses a light-shielding paper composed of a paper 75 to 80 xcexcm in thickness, 80 g/m as areal weight of a mixed pulp of 30% softwood pulp and 70% hardwood pulp made by a Fourdrinier paper machine, as a flexible sheet layer, a light-shielding LDPE resin inflation film 20 xcexcm in thickness containing 18 wt. % acetylene black laminated to one side of the paper through a polyurethane dry laminating adhesive layer, and a printing layer and a protection layer provided on the other side.
A packaging material disclosed in Japanese Patent 2676258 is a laminate comprising a coextruded multilayer film, wherein 0.03 to 0.6 wt. % a surfactant antistatic agent is incorporated into the surface layer.
However, the above conventional packaging materials are insufficient in the dispersion of light-shielding material, such as carbon black, and the generation of lumps and microgrits becomes a problem. Especially, in the case of high speed photographic photosensitive materials having an ISO photographic speed 100 or more, scuff marks, abrasion marks, pressure marks or the like generate by contacting the packaging material which contains lumps, microgrits, etc. with a photosensitive layer of the photographic photosensitive material, and they induce mortal troubles for photographic photosensitive materials. Furthermore, when the amount of light-shielding material is great, physical strength and heat sealing properties are degraded.
Besides, in order to pass the recent waste treatment of containers and packaging materials law, it is difficult to ensure antistatic properties or light-shielding ability by using a metal foil or a metallized flexible sheet layer provided with a deposited metal membrane. A means of solving the problem is to incorporate a large quantity, e.g. 10 wt. % or more, of conductive carbon black or graphite. However, the dispersion of them becomes further insufficient to generate lumps, microgrits or the like abundantly, and mortal troubles against photographic photosensitive materials frequently occur. Furthermore, the degradation of film moldability, pinholes or rupture also occurs, rendering to ensure light-shielding difficult. Moreover, heat sealing properties and physical strength are degraded. As mentioned above, the conventional packaging materials have problems as a packaging material for photographic photosensitive material and a package of photographic photosensitive material which is a precision chemical product, and an improvement is desired. Although it can be considered to use various rubbers which require crosslinking with sulfur, photographic properties of photographic photosensitive materials are affected adversely thereby.
An object of the invention is to solve the above problems, and to provide a packaging material for a photographic photosensitive material having good dispersion of carbon black, no generation of lumps and microgrits, good heat sealing properties and physical strength.
The present invention provides a packaging material for a photographic photosensitive material having a conductive light-shielding thermoplastic resin film layer which comprises a resin composition comprising 3 to 49 wt. % of a thermoplastic elastomer having a crystallinity of 40% or less measured by the X-ray diffraction method, 0.01 to 10 wt. % of lubricant, and 1 to 70 wt. % of carbon black which is acetylene carbon black or furnace carbon black.
In the above packaging material, by incorporating the thermoplastic elastomer having a crystallinity of 40% or less measured by the X-ray diffraction method in an amount of 5 wt. % or more, the dispersibility of carbon black is improved to prevent the generation of lumps and microgrits, and the degradation of physical strength and heat sealing properties are prevented, without affecting adversely photographic properties of photographic photosensitive materials.